A teacher who planted a fake bomb in a colleague's bag as a practical joke has been given a formal reprimand by his profession's governing body.
The General Teaching Council for Wales found that Geraint Lloyd Jones had acted unprofessionally.
The incident in 2008 led to Ysgol y Creuddyn secondary school near Llandudno, Conwy, being evacuated.
Technology teacher Mr Jones told the hearing at Ewloe, Flintshire, that he had acted "foolishly and stupidly".
He was formally cautioned by North Wales Police following the incident.
The misconduct panel said his actions amounted to behaviour that fell below the expectations that the profession and the public had of teachers to act responsibly.
The hearing was told that Mr Jones' actions led to a full-scale evacuation of pupils and staff after the fake device was found in a bag belonging to fellow teacher and friend, Richard Williams.
Mr Williams, who also taught technology at the school, described how he discovered the "bomb" when he placed his hand in the bag to retrieve a book for a pupil during a lesson.
"I heard a beep and saw a stopwatch - the timer had started," he told police in a statement.
"I would not be able to say if it was a fake or not."
Another colleague told the headteacher, and the school was evacuated while police headed to the scene.
The panel heard that the incident was treated so seriously because it followed a hoax bomb call to the school earlier in the day.
Giving evidence himself, Mr Jones admitted that it was this hoax call that had prompted him to devise the prank against his colleague.
But he insisted that the intention had been for his friend to open his bag in the office they shared during their lunchbreak.
"I had no intention to cause such trouble," he told the misconduct panel.
"I acted mindlessly and stupidly - I was playing a prank.
"It is extremely embarrassing and has caused great concern to me and my family."
Mr Jones said he offered his apologies to the school, its staff, pupils and governors, and also to the teaching panel.
The hearing heard that as soon as the incident came to light, he made a full confession to headteacher Dr Meirion Davies and police.
He was later given a formal caution by officers after the Crown Prosecution Service decided not to pursue Mr Jones through the courts.
He was also disciplined by his school, receiving a written warning.
However, the hearing was told that he continued to work at the school, was being supported by the head and staff, and had in fact been promoted to head of department since the incident.
Dr Davies gave evidence in support of Mr Jones, describing him as "conscientious" and "hard-working".
"It was immature and stupid, but there were no nasty intentions," Dr Davies told the panel.
"He is a very conscientious teacher, a very popular teacher, with his pupils and with his colleagues.
"His record, with this exception, is unblemished."
Imposing a formal reprimand, the chairman of the misconduct panel, Richard Parry Jones, said the support shown by the school had been taken into consideration in deciding on the penalty.